1. Field of the Invention
Embodiments of the present disclosure pertain to suspended structures and, in particular, to suspended structures fabricated by lithographic processes for use in microelectronic and micromechanical applications.
2. Description of the Related Art
Graphene, a single-layer, honeycomb lattice of carbon atoms, has recently emerged as a system of interest for fundamental studies in condensed-matter physics. Because of its unusual band structure, single-layer graphene is a zero-gap semiconductor with a linear energy dispersion relation. Under these circumstances, charges behave as substantially massless Dirac fermions and gives rise to novel phenomena, such as the half-integer quantum Hall effect. Technologically, graphene is a two-dimensional material with exceptional mobility, current-carrying capacity, and thermal conductivity, attracting significant attention to graphene as a promising post-silicon electronic material.
A remarkable electronic property of graphene is that both carrier type and density can be electrostatically controlled. Via the employment of a local gate and a global back gate, this feature allows in-situ creation and control of p-n or n-p-n junctions in graphene. These junctions have been demonstrated to induce band gaps in bi-layer graphene, partial equilibration of quantum Hall plateau, and have been predicted to give rise to Vaselago lensing, and Klein tunneling.
In most of the experiments to date, either organic or metal oxide layers have been used as the dielectric between graphene and local top gate. However, deposition of top gate dielectrics on a single atomic layer remains a delicate process, since impurities, defects and dopants may arise from deposition of the intervening layers.